Smashing the Protein "Speed Limit"
One of the oldest and most persistent "truisms" of bodybuilding is that you can't absorb more than 20 to 25 grams of protein in a single sitting. This belief, more than anything, probably gave rise to the seemingly universal bodybuilding habit of eating six or more meals a day.
How and why this belief came about is a mystery. No one, layperson or researcher, has been able to find any scientific evidence for this protein "speed limit." Nevertheless, most bodybuilders have put on their dietary seatbelts and abided by this limit for as long as practically anyone can remember.
What exactly did people think happened to any ingested protein beyond the 25-gram barrier? Did they conclude that it just turns into little protein bricks that are excreted? Sure, that's how Legos are made. Collect 'em over the years and build yourself a protein-Lego Death Star, complete with its own Count Dookie.
That explanation isn't much more plausible than any other, but maybe we can now blast through this mythical protein barrier, thanks to the work of sometime contributors to T Nation, Brad Schoenfeld and Alan Aragon.
Their new paper, in the Journal of the International Society of Sports Nutrition, resulted from an analysis of the collective research on the subject of protein utilization.
In it, they concluded that lifters interested in maximizing muscle protein synthesis should consume protein at a minimum rate of 0.4 g/kg per meal – spread across a minimum of 4 meals – in order to reach a minimum daily goal of 1.6 grams of protein per kilogram.
Those balls-out lifters who prefer to shoot for the daily goal of 2.2 grams of protein per kilogram (as supported by some of the literature) should take in 0.55 g/kg per meal, likewise spread across a minimum of 4 meals.
For a 200-pound man, that equates to:
- Minimum recommendation (0.4 g/kg/meal): 36 grams of protein per meal
- Maximum recommendation (0.55 g/kg/meal): 50 grams of protein per meal
Schoenfeld and Aragon point out that in dietary terms, the word "absorption" just describes the passage of nutrients from the gut into systemic circulation. By that definition, "The amount of protein that can be absorbed is virtually unlimited."
In the past, many researchers, in accordance with the old 20-25 gram per meal barrier, believed that any amount of protein beyond this amount was oxidized for energy or transaminated (a chemical reshuffling of amino acids) to form different compounds.
Schoenfeld and Aragon argue a different fate for "excess" protein. Following the digestion of a meal, the constituent amino acids (AA) are transported through specialized cells into hepatic portal circulation and the AA that aren't sucked up by the liver enter the bloodstream where they're free for the pickin' to any body tissues that want them.
And while the two scientists acknowledge that, at some point, consumption of higher protein doses results in greater AA oxidation, it's certainly not the fate of all additional ingested AAs.
To reiterate, Schoenfeld and Aragon concluded that it's a "relatively simple and elegant solution to consume protein at a target rate of 0.4 g/kg/meal across a minimum of four meals…"
And, for those who ascribe to the hypothesis that certain athletes need 2.2 grams of protein per kilogram per day, the two researchers recommended a protein intake of 0.55 g/kg/meal, spread across the same minimum four meals.
Let's assume the goal of 1.6 grams of protein per kilogram per day and look at the math:
- A 150-pound lifter would need to eat about 27 grams of protein per meal for 4 total daily meals.
- A 175-pound lifter would need to eat about 31 grams of protein per meal for 4 total daily meals.
- A 200-pound lifter would need to eat about 36 grams of protein per meal for 4 total daily meals.
- A 225-pound lifter would need to eat about 41 grams of protein per meal for 4 total daily meals.
Schoenfeld and Aragon don't specify how exactly lifters should get this large amount of protein, but it would seem like an impossible amount to ingest without the aid of a quality protein powder.
- Schoenfeld BJ et al. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018 Feb 27;15:10.